Exploring the brown adipose tissue in Congenital Generalized Lipodystrophy and Familial Partial Lipodystrophy

Abstract

Background: Lipodystrophy, similar to obesity, is a disease with white adipose tissue dysfunction, but with worse metabolic profile. The inherited lipodystrophies can be classified as generalized or partial, with the extent of adipose tissue loss being associated with the severity of the metabolic complications. Brown adipose tissue has different embryonic origin from WAT and the presence and functionality of brown adipose tissue on lipodystrophies is unknown. Objective: The aim of this study is to analyze the images of 18 F-FDG PET/CT scans conducted during the data collection for a doctoral project in patients with congenital generalized lipodystrophy and with familial partial lipodystrophy, with an emphasis on the anatomical regions of brown adipose tissue. Methods: 18F fluorodeoxyglucose coupled with computed tomography were performed on 17 patients with congenital generalized lipodystrophy and 13 patients with familial partial lipodystrophy for the evaluation of brown adipose tissue. The images were acquired after cold stimulation for two hours in a room acclimatized to 18 degrees Celsius, following the protocol proposed by BARCIST. The images will be analyzed using the Carimas software. For evaluation of BAT activity, ROIs will be drawn in the supraclavicular, cervical and axillary regions, with standardized uptake value e1,5 within the range of -190 to -10 Hounsfield Unit. Standardized uptake values will also be calculated for the brain, subcutaneous and visceral adipose tissue, perirenal region, liver and muscle. Perspectives: Information from clinical studies regarding the presence and functionality of brown adipose tissue in congenital lipodystrophies is scarce in the literature. Since the embryonic origin of brown adipose tissue and white adipose tissue is different, it is possible that these patients have preserved brown adipose tissue. Lipodystrophies are a group of diseases that present with difficult to control metabolic complications and limited therapeutic options. Understanding the presence and functionality of brown adipose tissue could open doors for future therapies centered on this tissue, if the presence in this group of diseases is confirmed.